Delft Spectral Technologies, an ADEM spin-off: “Roll out the technology worldwide”

Fast Optical Measurement System (FOMS): this is the name given to the tool for assessing the spectral characteristics of solar cells, and is developed and manufactured by Delft Spectral Technologies. Co-founder Jimmy Melskens laid the groundwork for the company while he was doing research at ADEM.

Electronic effects

The technology developed by Delft Spectral Technologies is a unique innovation in the world of solar energy and can measure all the colours of the spectrum. Using the Fast Optical Measurement System (FOMS), tests on solar cells can be performed more quickly and more accurately; an opportunity that Melskens seized with both hands during his research at ADEM. “During my research I focused on the optical characterization of amorphous silicon solar cells,” Melskens recalls. “It is well known that a key benefit of amorphous silicon solar cells is that they are very thin and can be produced in flexible rolls. Compared to the familiar blue solar panels, however, its competitiveness has deteriorated sharply in recent years. This is due to underperformance in terms of efficiency on the one hand, and the significant drop in costs for blue solar panels with crystalline silicon solar cells on the other.” But you’ll also find amorphous silicon in the very best crystalline silicon solar cells. “It is applied to the cells in very thin layers”, explains Melskens. “As part of my research for ADEM I studied electronic defects in materials. A certain amount of generated electricity is wasted as a result of such defects. In my research, I measured the effect of this using new technologies. And this then went on to form the basis for the company Delft Spectral Technologies.”

International publications

“The basic principle used in FOMS is a proven testing technology in the optical industry,” Melskens continues. “It’s called interferometry; measuring with the help of interference. You measure the spectral response of a solar cell by lighting it up electronically with a modulated light beam. This can be done very quickly. In contrast, the conventional testing technique is very slow because you have to measure the spectrum of each colour individually. You have to measure dozens of points, which takes 5 to 10 minutes. It was for precisely this reason that I developed a system based on the interferometer during my research, whereby an optical chip is used to measure solar cells extremely quickly, and by that I mean in a matter of seconds.”

Melskens’ publications about his research were included in various international scientific journals and led, as already mentioned, to the foundation of Delft Spectral Technologies. “And this year, for the very first time as a company, we presented our research results at the most important scientific solar trade fair in Europe; the EU PVSEC,” says Melskens.


Delft Spectral Technologies is currently also working on a prototype, which should be completed next year and will demonstrate how the technology works. This is being done in collaboration with a number of clients from the research community. “It was a deliberate decision not to initially focus on cell manufacturers,” explains Melskens. “It’s very difficult to enter China, where the majority of the manufacturers are based, with a completely new testing technology. They only want to use proven technologies for their mass production processes and they are not very open to adapting their measurement routines.” Yet there are plenty of benefits to Delft Spectral Technologies’ testing technology to be able to access these companies in the future. “Where flash tests approach their limit testing solar panels which are increasingly efficient, our technology doesn’t have a problem with that,” says Melskens. “We can also perform simultaneous reflection and transmission testing. This gives us a clear advantage compared to the traditional equipment which determines the External Quantum Efficiency (EQE, ed., ratio of the number of charge carriers and photons in a solar cell).”

Melskens concludes: “In 5 years’ time we want to have rolled out our technology both in Europe and across the world, and have achieved a market share of 10 percent. To this end, we have to prove that our testing technology enables a higher production output and that it can do more than just perform more measurements in a shorter time. After completion of the prototype, we want to start selling the first commercial systems in 2017.”

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